yes the 'thats why' is referring to the previous sentence, 'is the group within companies that buys other companies'. So he's saying 'hey this is the group that

yes the 'thats why' is referring to the previous sentence, 'is the group within companies that buys other companies'. So he's saying 'hey this is the group that buys other companies, if you're talking to them it's because they [maybe] want to buy you'. Not really clear though.